DESCENDING LIMB OF LOOP OF HENLE Meaning and
Definition
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The descending limb of the loop of Henle is an important component of the nephron, which carries out the process of urine formation within the kidneys. It is a thin, hairpin-shaped structure that extends from the cortex to the medulla of the kidney.
The primary function of the descending limb is to reabsorb water from the filtrate. It is highly permeable to water but almost impermeable to solutes, such as sodium and chloride ions. As the filtrate descends down the descending limb, the surrounding interstitial fluid becomes increasingly concentrated due to the active reabsorption of solutes, driven by the ascending limb of the loop of Henle. This osmotic gradient allows water to move out of the descending limb through osmosis, leading to water reabsorption and concentration of urine.
The descending limb also plays a role in the countercurrent mechanism, which is crucial for the formation of concentrated urine. The countercurrent exchange between the descending and ascending limbs allows for the maintenance of the osmotic gradient in the renal medulla, enhancing the overall efficiency of water reabsorption.
In summary, the descending limb of the loop of Henle is a key component of the nephron responsible for reabsorbing water from the filtrate and contributing to the concentration of urine through its permeability characteristics and involvement in the countercurrent mechanism.
